Components
Retina - Layer of light sensitive cells found at the back of the eye. Optic Nerve - nerve that connects eyes and the Brain. Sclera - White outer layer that supports the structures inside the eye. Cornea - See-through later at the front, allows light in and focuses light onto retina. Lens - Similar role to cornea but behind the iris. More for fine tune focus. Iris - Muscles surrounding the pupil that can change the pupils size. To get smaller the circular muscles recontract and the radial muscles relax. Ciliary Muscles & Suspensory Ligaments - Hold the lens in place and control it’s shape.
Accommodation
To focus on a near object
- The ciliary muscles contract
- The suspensory ligaments loosen The lens is then thicker and more curved- this refracts the light more.
To focus on a distant object
- The ciliary muscles relax
- The suspensory ligaments tighten The lens then becomes thinner- light is refracted less.
Vision Problems
Short sightedness is called myopia and is a result of the lens being too curved. Light is focused in front of the retina. Long Sightedness is called hyperopia and is a result of the lens being too flat. Light is focused behind the retina.